1. Field of the Invention
The present invention relates to a waveguide input apparatus of two orthogonally polarized waves. More particularly, the present invention relates to improvement of a waveguide input apparatus of two orthogonally polarized waves characterized in the structure of the waveguide input unit in a converter for satellite broadcasting and communication receiver to receive two electromagnetic waves, each having a plane of polarization orthogonal to each other, and a converter for satellite broadcasting and communication receiver (termed "for satellite broadcasting receiver" hereinafter) using such a waveguide of two orthogonally polarized waves.
2. Description of the Background Art
An example of a conventional waveguide input apparatus of two orthogonally polarized waves will be described hereinafter with reference to FIGS. 16A-16C. FIG. 16A is a cross sectional view taken along cross section S--S of FIG. 16C.
A waveguide input apparatus 90 for two orthogonally polarized waves includes a waveguide 90a for introducing a polarized wave, a probe 25 for receiving a vertically polarized wave, attached to waveguide 90a in a direction parallel to a plane of polarization 2 of a vertically polarized wave, a probe 26 attached to waveguide 90a in a direction parallel to a plane of polarization 3 of a horizontally polarized wave, a short bar 6, a circuit board 27 connected to probe 25 and arranged at a mount 29a in a manner orthogonal to probe 25, a circuit board 28 connected to probe 26 and arranged at a mount 29b in a manner orthogonal to probe 26, and a connecting portion 31 for connecting circuit board 27 and circuit board 28.
Waveguide 90a forms a short wall 8 at the inner wall. Two probes 25 and 26 are attached to waveguide 90a in a direction parallel to the two planes of polarization 2 and 3, respectively. The connection between probes 25 and 26 and circuit boards 27 and 28 is effected arranging respective components in an orthogonal manner (in skew lines). At the outer wall of waveguide 90a, mounts 29a and 29b from which probes 25 and 26 protrude, respectively, are provided. Circuit boards 27 and 28 are attached to mounts 29a and 29b, respectively. Plane of polarization 2 and plane of polarization 3 received by waveguide 90a are orthogonal to each other. The vertically polarized wave corresponds to plane of polarization 2, and the horizontally polarized wave corresponds to plane of polarization 3. Probe 25 and short bar 6 are provided to feed vertically polarized waves and transmit a polarized signal to the circuit board. Probe 26 and short wall 8 are provided to feed horizontally polarized waves and transmit a polarized signal to the circuit board.
Probes 25 and 26 receive two orthogonally polarized waves respectively. Probe 25 transmits the received polarized signal of plane of polarization 3 to circuit board 27. Probe 26 transmits the received polarized signal of plane of polarization 2 to circuit board 28. Circuit board 28 provides a polarized signal to circuit board 27 via connection portion 31. Circuit board 27 combines the polarized signal from probe 25 and the polarized signal from circuit board 28.
Another example of a waveguide input apparatus of two orthogonally polarized waves will be described with reference to FIGS. 17A-17C. FIG. 17A is a sectional view taken along a cross section T--T of FIG. 17C.
A waveguide input apparatus 100 of two orthogonally polarized waves includes a waveguide 110a, probes 34 and 35 attached in a direction parallel to the two planes of polarization 2 and 3 orthogonal to each other, respectively, and a circuit board 32 connected to probes 34 and 35, and arranged at a mount 33 at an angle of approximately 45.degree. to probes 34 and 35, respectively.
Mount 33 of circuit board 32 formed at the outer wall of waveguide 100a has circuit board 32 attached so as to be 45.degree. with respect to the two planes of polarization 2 and 3. Therefore, the two signals from two probes 34 and 35 are received by one circuit board 32. More specifically, probes 34 and 35 receive two orthogonally polarized waves respectively. Probe 34 transmits the received polarized signal of plane of polarization 2 to circuit board 32. Probe 35 transmits the received polarized signal of plane of polarization 3 to circuit board 32. Circuit board 32 combines these polarized signals.
In order to amplify and combine the signals received at probes 25 and 26 for output in the waveguide input apparatus having an input structure described with reference FIGS. 16A-16C, a circuit for supplying the signals from probes 25 and 26 to respective one of circuit boards 27 and 28 must be provided. Moreover, a signal combine means at one circuit board 27 is needed and a signal from the other circuit board 28 must be transmitted to circuit board 27 with the combine means via a connection portion 31.
The above-described transmission of a signal will increase the complexity of the circuit patterns and structures. Furthermore, there is a possibility of increasing signal loss and inducing interference since a polarized signal has an extremely high frequency. The circuit design may be extremely difficult since critical factors must be taken into account for the arrangement of the circuit pattern. In the assembly of a waveguide, two circuit boards 27 and 28 must be attached, and particular care must be exerted from the standpoint of high frequency for connecting the boards to connection portion 3. The task thereof is difficult, resulting in increase of the cost.
The waveguide input apparatus having the input structure described with reference to FIGS. 17A-17C is advantageous in that wiring for connecting two boards is not required since there is only one board. However, this apparatus requires the precise provision of (two) holes for insertion of probes 34 and 35 at 45.degree. about the center plane with respect to mount 33 of circuit board 32. The structure design of the mount will become complicated. Also, a working skill of a high level is indispensable. This means that the working task will become difficult with a more complex assembly task. As a result, the fabrication cost will be increased. Also, variation in the quality of the mass production becomes greater, so that the performance requirement cannot be met unless adjustment is carried out for each apparatus.
A converter for satellite broadcasting receiver is known as an apparatus utilizing such a waveguide apparatus of two orthogonally polarized waves. The converter for satellite broadcasting receiver has the above-described problems of the waveguide apparatus of two orthogonally polarized waves.